Method for enhanced electrotransport agent delivery

ABSTRACT

An electrotransport composition comprises at least one C 2  -C 4  lower alcohol, unsaturated derivatives thereof, or mixtures thereof, and at least one C 8  -C 14  higher alcohol, unsaturated derivatives thereof, or mixtures thereof. An electrotransport device and a method of increasing transdermal electrotransport flux utilize the composition of the invention for delivering pharmaceutically-acceptable agents across a body surface such as skin.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates generally to permeation enhancers forelectrotransport agent delivery. More particularly, this inventionrelates to compositions comprising different alcohols as permeationenhancers. These compositions may be incorporated into electrotransportdevices for the delivery of agents, such as drugs and prodrugs, througha body surface.

2. Background Art

Drugs are most conventionally administered either orally or byinjection. Unfortunately, many medicaments are completely ineffective orof radically reduced efficacy when orally administered since they eitherare not absorbed or are adversely affected before entering the bloodstream and thus do not possess the desired activity. On the other hand,the direct injection of the medicament into the blood stream, whileassuring no modification of the medicament in administration, is adifficult, inconvenient and uncomfortable procedure, sometimes resultingin poor patient compliance. Transdermal drug delivery offersimprovements in these areas. The term "transdermal" is used herein inits broadest sense as the delivery of an agent through a body surface,such as the skin, mucosa, or nails. There are two major types oftransdermal agent delivery, one driven by a concentration-gradient force(passive transdermal delivery), and the other driven, in addition, by aforce created by applying an electrical potential (electrotransportdelivery).

The term "passive" transdermal delivery, is used herein to describe thepassage of an agent through a body surface, eg, skin, in the absence ofan applied electrical current. Typically, passive delivery devices havea drug reservoir which contains a high concentration of a drug. Thedevice is placed in contact with a body surface for an extended periodof time, and is allowed to diffuse from the reservoir and into the bodyof the patient, which has a much lower concentration of drug. Theprimary driving force for passive drug delivery is the concentrationgradient of the drug across the skin. In this type of delivery, the drugreaches the bloodstream by diffusion through the dermal layers of thebody. The preferred agents for passive delivery are hydrophobicnon-ionic agents, given that the drug must diffuse through the lipidlayers of the skin.

The term "electrotransport" is used herein to describe the passage of asubstance, eg, a drug or prodrug, through a body surface or membrane,such as the skin, mucous membranes, or nails, induced at least partiallyby the application of an electric field across the body surface (eg,skin). A widely used electrotransport process, iontophoresis, involvesthe electrically induced transport of therapeutic agents in the form ofcharged ions. Ionizable therapeutic agents, eg, in the form of a saltwhich when dissolved forms charged agent ions, are preferred foriontophoretic delivery because the charged agent ions move byelectromigration within the applied electric field. Electroosmosis,another type of electrotransport process, involves the movement of aliquid, which liquid contains a charged and/or uncharged therapeuticagent dissolved therein, through a biological membrane under theinfluence of an electric field. Another type of electrotransport,electroporation, involves the formation of transiently-existing pores ina living biological membrane under the influence of an electric fieldand delivery of a therapeutic agent therethrough. However, in any givenelectrotransport process, more than one of these processes may beoccurring simultaneously to some extent. Accordingly, the term"electrotransport" is used herein in its broadest possibleinterpretation to include the electrically induced or enhanced transportof at least one agent, which may be charged, ie, in the form of ions, oruncharged, or of mixtures thereof, regardless of the specific mechanismsby which the agent is actually transported.

A common goal in both passive and electrotransport delivery is toenhance the rate of delivery of the agent. A further goal inelectrotransport delivery is to reduce the electrical resistance of theskin or other body surfaces, so that the power requirements for a givenlevel of applied electric current or drug flux will be lowered. The term"permeation enhancer" is used herein to describe additives which causean increase in drug delivery rates both in passive and electrotransportdelivery, regardless of whether the enhancement occurs by reduction ofelectrical or diffusional resistance.

Although there are similarities between electrotransport and passivetransdermal delivery, there are also substantial differences. Onedifference relates to the different pathways utilized for deliverythrough the skin by the passive and electrotransport induced processes.Transdermal electrotransport delivery of an agent occurs within thehydrophilic pathways through the skin, ie, the sweat ducts, around hairfollicles, and/or through pores, because these are the paths of leastelectrical resistance. On the other hand, passive transdermal deliveryoccurs primarily by direct diffusion through the lipid layers of theskin. Accordingly, an ideal passive permeation enhancer will disrupt thelipid layers of the skin, while an ideal electrotransport enhancer willpreferably decrease the electrical resistance of the existinghydrophilic pathways in the skin. (See, Rolf, D., "Chemical and PhysicalMethods of Enhancing Transdermal Drug Delivery," PharmaceuticalTechnology, pp 130-140 (September 1988); Cullander, C., "What are thePathways of lontophoretic Current Flow through Mammalian Skin?",Advanced Drug Delivery Reviews, 9:119-135 (1992)).

Thus, it is not surprising that many passive permeation enhancers do notenhance electrotransport delivery rates. For instance, Hirvonen et alindicate that N, N-dimethylamino acetate (DDAA) and azone increase therate of passive permeation of the agent sotalol relative to thatobtained with sotalol alone (control). (Hirvonen et al, "TransdermalPermeation of Model Anions and Cations: Effect of Skin Charge,lontophoresis and Permeation Enhancers", Proceed. Intern. Symp. Control.Rel. Bioact. Mater., 19:452 (1992)). And the passage of an electriccurrent was also shown to increase the rate of delivery of sotalolcompared to that of its passive rate (control). However, the addition tosolatol of either DDM or azone reduced the rate of electrotransport ofsolatol compared to its rate of electrotransport without DDAA or azone(control). Clearly, DDAA and azone, both known passive permeationenhancers, were not only inoperative in electrotransport, but theyactually reduced the rate of electrotransport delivery of the agent.Kontturi et al indicated that the aforementioned passive enhancers, infact, increase skin resistivity, and advanced that passive enhancerssuch as those are inappropriate for use in electrotransport drugdelivery. (Kontturi et al, "Electrochemical Characterization of HumanSkin by Impedance Spectroscopy: The Effect of Penetration Enhancers",Pharmaceutical Research 10(3):381-385 (1993)).

Other permeation enhancers have been disclosed to be useful in passivetransdermal delivery. For example, WIPO Laid Open Patent Application WO91/16930 to Ferber et al discloses that an aqueous solution of up to 40v/v% lower alcohol and higher alcohol in a saturating amount is suitablefor enhancing passive transdermal delivery. Suitable passive transdermaldelivery enhancers disclosed therein are lower C₂ -C₄ alcohols such asethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol, and higheralcohols such as C₆ -C₁₄ alcohols including 1-hexanol, 1-octanol,1-nonanol, 1-decanol, 1-undecanol, 1-dodecanol, 1-tridecanol,1-tetradecanol, 4-methyl-1-pentanol, 5-methyl-1-heptanol,3,3-dimethyl-1-octanol, 3-cyclopentyl-1-propanol, cis-3-hexen-1-ol,trans-3-hexen-1-ol, 9-decen-1-ol and 2-octanol.

The number of permeation enhancers disclosed as useful inelectrotransport delivery is considerably more limited. Ethanol, forinstance, has been used as a permeation enhancer for theelectrotransport delivery of polypeptides is discussed by Srinivasan etal (Srinivasan et al, "lontophoresis of Polypeptides: Effect of EthanolPretreatment of Human Skin," J. Pharm. Sci. 79(7):588 (July 1990)).Surfactant (eg, sodium lauryl sulfate) permeation enhancers forelectrotransport drug delivery are disclosed in Sanderson et al, U.S.Pat. No. 4,722,726 and fatty acid (eg, oleic acid) permeation enhancersfor electrotransport drug delivery are disclosed in Francoeur et al,U.S. Pat. No. 5,023,085.

Thus, in general, there is still a need for compositions which reducethe electrical resistance of the skin and, thus, increase agentelectrotransport therethrough, producing an enhancement of the deliveryrate of the agent while reducing the power requirements of theelectrotransport device and/or the area of contact between the deviceand the body surface.

DISCLOSURE OF THE INVENTION

This invention arose from a desire to improve on prior art technology inthe field of transdermal electrotransport delivery. This inventionprovides a composition that enhances the electrotransport flux of a drugor prodrug through a body surface such as skin. The permeation enhancingcomposition comprises in combination (1) at least one lower alcohol and(2) at least one higher alcohol, both of which may be linear branched,aromatic, and/or cyclic. The lower alcohol is preferably a C₂ -C₄alkanol or unsaturated derivatives thereof, and more preferably ethanol.The higher alcohol is preferably a C₈ -C₁₄ alkanol or unsaturatedderivatives thereof, more preferably a C₁₀ -C₁₂ alkanol or unsaturatedderivatives thereof. Of these higher alcohols, dodecanol and 1-dodecanolare most preferred.

The composition of the invention reduces the electrical resistance ofbody surfaces, such as the skin, mucosa, and nails, duringelectrotransport agent delivery, and permits a reduction in the size ofthe delivery device and/or the power (ie, voltage) required to maintaina particular level of electrotransport current and rate ofelectrotransport agent delivery.

The present composition is suitable for use in reducing the electricalresistance of the body surface (eg, skin) site adjacent the donorelectrode of an electrotransport delivery device, the skin site adjacentthe counter electrode of the device, or both body surface sites. Thepermeation enhancer composition may be applied to the body surface priorto or during agent delivery, but the composition is preferably placed inthe donor and/or counter reservoir of an electrotransport deliverydevice and is delivered to the body surface simultaneously with theagent.

Also provided herein is an electrotransport delivery device comprisingdonor and counter electrodes, at least one of the electrodes having areservoir comprising the lower/higher alcohol composition, an electricalpower source which is electrically connected to the donor and counterelectrodes, and optionally electronic control circuitry.

The composition of the present invention may be used with differentelectrotransport devices for the delivery of a variety ofpharmaceutically acceptable agents, including those specificallydisclosed herein. One particular application for which the compositionis most suitable is the electrotransport delivery of amine and aminoacid containing agents.

This invention will now be described in further detail with reference tothe accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a sectional view of one embodiment of an electrotransportdevice suitable for use with the permeation enhancing composition of thepresent invention.

MODES FOR CARRYING OUT THE INVENTION

This invention arose form a desire to improve on prior art technologyfor the transdermal delivery of pharmaceutically-acceptable agents, suchas drugs or prodrugs, suitable for the prevention or treatment ofdisease in humans. The present technology has particular application inthe field of electrotransport delivery of pharmaceutically-acceptableagents (eg, drugs) and particularly agents containing amine groupsand/or peptide groups.

This present invention, thus, provides a transdermal electrotransportpermeation enhancing composition, comprising at least one lower alcohol,preferably a C₂ -C₄ alkanol or unsaturated derivatives thereof, ormixtures thereof, and at least one higher alcohol, preferably a C₈ -C₁₄alkanol or unsaturated derivative thereof, or mixtures thereof. Analcohol, as used herein, is defined as an alkyl compound having at leastone hydroxyl (--OH) group, which may be saturated or unsaturated,linear, branched, cyclic and/or aromatic. This definition also includespolyhydric alcohols having more than one hydroxyl group, such as glycolsor diols. A "higher alcohol", as used herein, refers to a straight orbranched chain or cyclic C₈ -C₁₄ alcohol. The higher alcohol may be aprimary, secondary or tertiary alcohol. Examples of higher alcoholsinclude, without limitation, 1-dodecanol, 3-dodecanol, 1-decanol,1-undecanol, 3-butyl-1-octanol, 4-pentyl-1-hexanol, and5-propyl-2-decanol. The higher alcohol is preferably a straight chainalcohol having 10 to 12, and more preferably 12, carbon atoms. Preferredas a higher alcohol is dodecanol, and still more preferred is1-dodecanol. A "lower alcohol", as used herein, encompasses an alcoholpreferably having 2 to 4 carbon atoms. The lower alcohol may be aprimary, secondary or tertiary alcohol including, without limitation,ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butyl alcohol,and unsaturated derivatives thereof. More preferably, the lower alcoholis ethanol or propanol, and still more preferably it is ethanol. Thealcohols of the composition of this invention may have othersubstituents which do not interfere with the electrotransport deliveryenhancing characteristics of the composition. The combination of thelower and higher alcohols in an electrotransport composition produces anunexpected enhancement of the transdermal electrotransport drug flux,which is accompanied by an unexpected reduction in skin resistanceduring electrotransport drug delivery, when compared with the drug fluxand skin resistance when electrotransporting drug in the presence ofeither the lower alcohol or the higher alcohol alone.

An increase in the delivery rate of the agent and a decrease in theelectrical resistance of the body surface are achieved by contacting theagent (eg, drug) to be delivered and the composition with the bodysurface while applying an electrical current through the composition,the agent, and the body surface. More preferably, the composition of theinvention is added directly to the donor reservoir, counter reservoir,or both reservoirs of an electrotransport delivery device. However, thebody surface may also be treated with the lower/higher alcoholcomposition prior to the electrotransport delivery of the drug. Inaddition, it is possible to apply the lower/higher alcohol compositionto the body surface after electrotransport delivery of the agent hasbeen initiated.

The concentration of the higher alcohol in the fully hydrated donorreservoir, ie, under reservoir conditions immediately prior to use, ispreferably about 0.01 to 100 millimolar (mM). More preferably, thehigher alcohol concentration is about 1 to about 50 mM, and still morepreferably greater than 10 mM. The concentration of the lower alcohol inthe donor reservoir is preferably about 0.5 to 30% (v/v), morepreferably less than about 25% (v/v), and still more preferably, 10 to25% (v/v). In one particularly preferred form of the device, thecomposition present in the donor reservoir preferably containssufficient water to achieve greater than 50% ionization of the agent tobe delivered. The concentration of the pharmaceutically-acceptable agentto be delivered may vary substantially, depending on the type of drug,its potency, and the like. The concentration of the agent in the fullyhydrated donor reservoir is generally about 1 microgram/mL (μg/mL) to100,000 μg/mL, and more preferably about 1000 μg/mL to about 50,000μg/mL. Furthermore, the donor reservoir may contain other chemicalspecies such as buffering agents, antioxidants, antimicrobial agents andagents that further increase the conductivity of the body surface or itspermeability, and the like. Other suitable additives may be chosen toincrease drug solubility and/or increase charged ion concentration. Thedonor reservoir may also contain additives which inhibit microbialgrowth or perform other functions unrelated to the delivery of theagent.

This invention is useful in the delivery of drugs or prodrugs within abroad class that are deliverable through body surfaces and membranes,including the skin, mucosa and nails. As used herein, the expressions"agent", "drug" and "prodrug" are used interchangeably, and are intendedin their broadest interpretation as any pharmaceutically-acceptablesubstance which may be delivered to a living organism to produce adesired, usually beneficial, effect. In general, this includestherapeutic agents in all of the major therapeutic fields including, butnot limited to, anti-infectives such as antibiotics and antiviralagents; analgesics such as fentanyl, sufentanil, and buprenorphine, andanalgesic combinations; anesthetics; anorexics; antiarthritics;antiasthmatic agents such as terbutaline; anticonvulsants;antidepressants; antidiabetics agents; antidiarrheals; antihistamines;antiinflammatory agents; antimigraine preparations; antimotion sicknesspreparations such as scopolamine and ondansetron; antinauseants;antineoplastics; antiparkinsonism drugs; antipruritics; antipsychotics;antipyretics; antispasmodics including gastrointestinal and urinary;anticholinergics; sympathomimetrics; xanthine derivatives;cardiovascular preparations including calcium channel blockers such asnifedipine; betaagonists such as dobutamine and ritodrine; betablockers; antiarrythmics; antihypertensives such as atenolol; ACEinhibitors such as ranitidine; diuretics; vasodilators includinggeneral, coronary, peripheral and cerebral; central nervous systemsstimulants; cough and cold preparations; decongestants; diagnostics;hormones such as parathyroid hormones; hypnotics; immunosuppressives;muscle relaxants; parasympatholytics; parasympathomimetrics;prostaglandins; proteins; peptides; psychostimulants; sedatives andtranquilizers.

More specifically, this invention is useful for the controlled deliveryof baclofen, beclomethasone, betamethasone, buspirone, cromolyn sodium,diltiazem, doxazosin, droperidol, encainide, fentanyl, hydrocortisone,indomethacin, ketoprofen, lidocaine, methotrexate, metoclopramide,miconazole, midazolam, nicardipine, piroxicam, prazosin, scopolamine,sufentanil, terbutaline, testosterone, tetracaine, and verapamil, amongother drugs.

The invention is particularly useful in the controlled delivery ofpeptides, polypeptides, proteins, or other macromolecules difficult todeliver transdermally or transmucosally because of their size. Thesemacromolecular substances typically have a molecular weight of at leastabout 300 Daltons, and more typically, in the range of about 300 to40,000 Daltons. Examples of peptides and proteins which may be deliveredin accordance with the present invention include, without limitation,LHRH, LHRH analogs such as buserelin, gonadorelin, naphrelin andleuprolide, GHRH, GHRF, insulin, insulinotropin, heparin, calcitonin,octreotide, endorphin, TRH, NT-36 (chemical name: N-(s)-4-oxo-2-azetidinyl!carbonyl!-L-histidyl-L-prolinamide!, liprecin,pituitary hormones (eg, HGH, HMG, HCG, desmopressin acetate), follicleluteoids, α-ANF, growth factor releasing factor (GFRF), β-MSH,somatostatin, bradykinin, somatotropin, platelet-derived growth factor,asparaginase, bleomycin sulfate, chymopapain, cholecystokinin, chorionicgonadotropin, corticotropin (ACTH), erythropoietin, epoprostenol(platelet aggregation inhibitor), glucagon, hirudin and hirudin analogssuch as hirulog, hyaluronidase, interferon, interleukin-2, menotropins(urofollitropin (FSH) and LH), oxytocin, streptokinase, tissueplasminogen activator, urokinase, vasopressin, desmopressin, ACTHanalogs, ANP, ANP clearance inhibitors, angiotensin II antagonists,antidiuretic hormone agonists, antidiuretic hormone antagonists,bradykinin antagonists, CD4, ceredase, CSF's, enkephalins, FABfragments, IgE peptide suppressors, IGF-1, neurotrophic factors, colonystimulating factors, parathyroid hormone and agonists, parathyroidhormone antagonists, prostaglandin antagonists, pentigetide, protein C,protein S, renin inhibitors, thymosin alpha-1, thrombolytics, TNF,vaccines, vasopressin antagonist analogs, alpha-1 antitrypsin(recombinant), and TGF-beta.

One example of an electrotransport device suitable for use with thepresent invention is illustrated in FIG. 1. Device 10 has two currentdistributing members or electrodes, comprised of electrically conductivematerials, referred to herein as donor electrode 12 and counterelectrode 14. The electrodes may be composed of any materials which aresufficiently electrically conductive, including without limitation,silver, silver chloride, zinc, carbon, and stainless steel. Theelectrodes may be present in a variety of forms including a metal foilor screen, a polymer film having an electrically conductive coating or apolymer matrix containing an electrically conductive filler, eg,powdered carbon or metal, formed by conventional processes such asextruding, calendering, film evaporation, or spray coating. In FIG. 1,the donor and counter electrodes 12 and 14 are positioned adjacent to,and in electrical contact with, donor reservoir 16 and counter reservoir18, respectively. The donor reservoir 16 contains a solution of thebeneficial agent (eg, a drug) to be delivered, while the counterreservoir 18 contains a solution of a biocompatible electrolytic saltsuch as sodium chloride or optionally another beneficial agent to bedelivered. The reservoirs 16 and 18 are formed of any material adaptedto absorb and hold a sufficient quantity of liquid therein in order topermit the passage of the agent therethrough by electrotransport. Sincewater is the preferred liquid solvent for forming the solutionscontained in reservoirs 16 and 18, the reservoirs preferably contain oneor more hydrophilic polymers such as polyvinylpyrrolidone, polyvinylalcohol, or polyethylene glycols, optionally mixed with a hydrophobicpolymer such as polyisobutylene, polyethylene, and/or polypropylene. Anelectrical insulator 20 is positioned between (i) the donor electrode 12and the donor reservoir 16, and (ii) the counter electrode 14 and thecounter reservoir 18. The insulator 20, may be an air gap or a materialwhich conducts neither electrons nor ions to a substantial extent, andprevents the device 10 from short-circuiting through a path which doesnot include the body surface 40, to which the device 10 is applied. Thedevice 10 optionally includes a backing layer 22 composed of aliquid-impermeable non-conducting material. The device 10 has anelectronic circuit, illustrated schematically in FIG. 1 as layer 24,having an electric power source, eg, one or more batteries, therein.Typically, the electronic circuit layer 24 is relatively thin and ispreferably comprised of electronically conductive pathways, which areprinted, painted or otherwise deposited on a thin, flexible substratesuch as, for example, a film or polymeric web. The electronic circuitlayer 24 is, for example, a printed flexible circuit. In addition to thepower source, the electronic circuit layer 24 may also include one ormore electronic components which control the level, waveform shape,polarity, timing, etc, of the electric current applied by the device 10.For example, the circuit layer 24 may contain one or more elements ofcontrol circuitry such as a current controller, eg, a resistor or atransistor-based current control circuit, an on/off switch, and/or amicroprocessor adapted to control the current output of the power sourceover time. The outputs of the circuit layer 24 are electricallyconnected to the electrodes 12 and 14, so that at any one time eachelectrode is in electrical contact with an opposite pole of the powersource within the circuit layer 24.

In this embodiment, the device 10 adheres to the body surface by meansof a peripheral adhesive layer 28. The device may optionally contain anin-line adhesive layer, ie an ion-conducting adhesive layer positionedbetween reservoirs 16, 18 and the body surface, eg, the skin surface. Anin-line adhesive must be composed of an ion-transmitting material, iebeneficial agent ions must be capable of passing through the adhesivelayer to reach the body surface. Optional flux control membranes 30 and32, such as those disclosed in Theeuwes et al, U.S. Pat. Nos. 5,080,646;5,147,296; and 5,169,382, are positioned between the donor reservoir 16and the body surface 40 and between the counter reservoir 18 and thebody surface 40, respectively, in order to limit or control the amountof passive, ie non-electrically assisted, flux of agent to the bodysurface 40.

The invention will be further described by reference to the followingexamples, wherein human cadaver skin electrical resistivity and drugflux were measured for various permeation enhancer compositions.

EXAMPLES Preparation of Human Cadaver Skin

Skin strips having a thickness of 1 mm were removed from a human cadaverwith an electric dermatome. These skin strips were placed inpolyethylene bags, sealed and placed in a refrigerator at 4° C. fortemporary storage. Prior to use in an electrotransport cell, the skinstrips were placed in 1 liter beakers containing water at 60° C. forabout 90 seconds, and gently stirred. The skin strips were then removed,and placed onto the absorbent side of a piece of BENCHKOTE fabric withtheir dermis side down. The epidermis was removed from each strip with around-tip spatula, and flat tipped tweezers to retain the dermis. Eachepidermis, stratum corneum side up, was then transferred to a 5 cm deepPYREX glass tray filled with water. Each floating epidermis wasstretched essentially flat, and then removed from the water, and 2.2 cmdiameter disks of each epidermis were punched out of areas having noobservable surface damage. The disks were stored at 4° C. in a sealedcontainer with water droplets to maintain their moisture.

Experimental Set-up for Electrotransport

The disks were mounted between the donor and receptor compartments, withthe stratum corneum side facing the donor compartment, of a2-compartment polycarbonate electrotransport permeation cell. The volumeof each compartment was about 2 mL and the area between the twocompartments, ie, the exposed area for transport, was about 1.26 cm².

An aqueous solution of the drug being transdermally delivered and theselected permeation enhancer composition, if any, was placed in thedonor compartment. Dulbecco's phosphate buffered saline (approximately0.15N NaCl, pH 7.0) was placed in the receptor compartment.

The rate of transport of drug and the electrical resistance of the skinwere monitored throughout the experiments while applying an electriccurrent.

The cell was maintained at 32° C. by a Haake Model D1 heatingblock/water bath. The electrodes were connected to a galvanostat, whichapplied a constant current of 126 μA (current density of 100 μA/cm²) andmonitored the voltage drop across the skin by placing two Ag/AgCljunction reference electrodes, one each in the donor and receptorsolutions, and measuring the voltage difference (AV) between theelectrodes.

The resistance of the skin (R) was obtained from Ohm's law:

R=ΔV/i

where i equals the applied current (ie, 126 μA).

Example 1 Enhanced Effect of Composition of the Invention Over EitherComponent Alone on Agent Flux and Skin Resistance

The following experiments were conducted to assess the effect of onecomposition of the invention, containing ethanol and dodecanol, on thetransdermal delivery of sodium ketoprofen (ketoprofen anions) byelectrotransport from a cathodic electrode. The electrotransportdelivery of ketoprofen in the presence of various enhancers was assessedside-by-side for comparative purposes. The enhancers used were asfollows: (i) ethanol alone; (ii) dodecanol alone; (iii) no enhancer;(iv) ethanol and dodecanol. The initial concentration of ketoprofen inthe donor compartment was 100 mg/mL, and the donor solution had a pH(unbuffered) of 5.0 to 5.5. A silver chloride composite polymerelectrode (cathode) was placed in the donor compartment, and a silverfoil electrode (anode) was placed in the receptor compartment.

Each experiment was started by connecting the power source to theelectrodes, and samples were automatically taken from the receptorcompartment every one to two hours, except for overnightexperimentation, using an Isco Model 2230 autosampler and a meteringpump. The concentration of ketoprofen in the samples was determined byhigh performance liquid chromatography (HPLC) using a Shimadzu ModelSCL-6B chromatograph. Each run was conducted in triplicate, includingthe control, to minimize errors. All cells were set-up with tissue fromthe same cadaver. The selected permeation enhancer composition wasplaced in the donor compartment, while the control cell's donorcompartment contained no enhancer.

Flux and voltage measurements generally reached steady state after about4 hours of cell operation. The steady state flux values and calculatedskin resistances are shown in Table 1 in normalized form, ie, all valuesare divided by their respective control value.

                  TABLE 1    ______________________________________    Comparison of Effect on Agent Flux and Skin Resistance    of Lower or Higher Alcohol Alone, and    Composition of Invention                    Normalized                    Ketoprofen                              Normalized Skin    Permeation Enhancer(s)                    Flux      Resistance    ______________________________________    Control (No Enhancer)                    1.00      1.00    Ethanol (25% v/v)                    1.24      0.47    Dodecanol (<100 mM)                    1.93      0.39    Dodecanol (<100 mM)                    10.15     0.06    and Ethanol (20% v/v)    ______________________________________

As Table 1 above illustrates, the addition of ethanol alone produced areduction in skin resistance to 0.47 with respect to 1 for the control(more than a 50% reduction in skin resistance), while the addition ofdodecanol alone produced a reduction in skin resistance to 0.39 withrespect to the value of 1 for the control (almost a 60% reduction inskin resistance).

The composition containing both dodecanol and ethanol, however, producedan unexpectedly greater reduction in skin resistance to only 0.06 withrespect to the value of 1 for the control (a reduction in skinresistance of greater than 94%). In addition, ethanol alone increasedthe rate of delivery of ketoprofen by only 24%, and dodecanol aloneincreased it by 93%. The ethanol/dodecanol composition, representativeof the invention, produced an unexpected enhancement of ketoprofenelectrotransport flux, which was more than 10 times greater than thecontrol.

Although ethanol is present in slightly different amounts when testedalone (25% v/v) and with dodecanol (ethanol 20% v/v) as an enhancer,this difference in its concentration does not significantly alter itseffect. This is confirmed in Example 2.

Example 2 Measurement of Metoclopramide Flux With Ethanol/Dodecanol asEnhancer in Comparison With Ethanol Alone as Enhancer (Comparison ofInvention With Prior Art)

The experimental conditions were identical to those described in Example1, except an aqueous solution of metoclopramide HCl, instead of sodiumketoprofen, was placed in the donor compartment. In addition, the silverchloride cathode was placed in the receptor compartment and the silverfoil anode was placed in the donor compartment since metoclopramide ionsare cationic as opposed to ketoprofen ions which are anionic. Theconcentration of metoclopramide in the donor solution was about 100 mgmetoclopramide/mL, and saline pH 7 was placed in the receptorcompartment. The system was maintained at 32° C. and a constant electriccurrent of 100 μA/cm² was applied throughout the procedure.

All runs had the same concentration of agent and other conditions,except for the following shown in Table 2.

                  TABLE 2    ______________________________________    Content of Enhancer (Ethanol), Metoclopramide    Flux and Cell Voltage                         Normalized    Enhancer             Metoclopramide                                     Normalized                  Amt          Mass Flux Skin Resistance    #    Type     (wt %)  n    (after 5 hrs)                                         (after 5 hrs)    ______________________________________    1    None      0      1    1.00      1.00    2    Ethanol  10      3    0.86      1.32    3    Ethanol  20      3    0.73      1.13    4    Ethanol  30      3    0.93      1.26    5    Dodecanol                   2         Ethanol  30      3    1.55      0.50    ______________________________________

The mass flux and skin resistance values were normalized versus thecontrol. The second column from the right shows the normalized valuesversus the electrotransport flux of metoclopramide in the absence of anypermeation enhancer (first line). The skin resistance (which wascalculated from the measured cell voltage ΔV using Ohm's law, R=i/ΔV)was also normalized with respect to the value obtained byelectrotransport of metoclopramide in the absence of any permeationenhancer (rightmost column). These values have been provided to permit acomparison with the values for the permeation enhancing compositionsshown in Table 1. For example, when dodecanol was utilized in thepresence of 30 wt% ethanol, the electrotransport mass flux ofmetoclopramide was enhanced by over 50% and the skin resistance waslowered to one-half the resistance of the control. However, the use ofethanol alone as a flux enhancer is shown in Table 2 not to enhance, butto actually decrease, the mass flux of metoclopramide and increase theresistance of the skin during electrotransport delivery ofmetoclopramide.

Having thus generally described the invention, and described in detailcertain preferred embodiments thereof, it will be readily apparent thatvarious modifications to the invention may be made by those skilled inthe art without departing from the scope of this invention, which islimited only by the following claims.

We claim:
 1. A method of enhancing electiotransport flux of a beneficialpharmaceutically acceptable agent through a body surface,comprising:placing a composition in contact with the body surface, thecomposition comprising an agent in a form suitable for electrotransportdelivery; at least one C₈ -C₁₄ linear, branched, cyclic or aromaticalcohol or unsaturated derivatives thereof, or mixtures thereof, and atleast one C₂ -C₄ alcohol or unsaturated derivatives thereof, or mixturesthereof; and applying an electric field across the composition and thebody surface, whereby the agent is delivered through the body surface byelectrotransport at a flux greater than in the absence of the alcohols.2. The method of claim 1, further comprising dissolving the agent in anaqueous solvent.
 3. The method of claim 1, wherein the C₈ -C₁₄ alcoholor unsaturated derivative thereof is present in an amount of about 0.01to 100 mM; andthe C₂ -C₄ alcohol or unsaturated derivative thereof ispresent in an amount of about 0.5 to 30% (v/v).
 4. The method of claim1, wherein the C₈ -C₁₄ alcohol or unsaturated derivative thereof ispresent in an amount of about 1 to 50 mM; andthe C₂ -C₄ alcohol orunsaturated derivative thereof is present in an amount of about 1 to 20%(v/v).
 5. The method of claim 1, wherein the C₂ -C₄ alcohol comprisesethanol.
 6. The method of claim 1, wherein the C₈ -C₁₄ alcohol comprisesdodecanol.
 7. The method of claim 6, wherein the dodecanol comprises1-dodecanol.
 8. The method of claim 1, wherein the agent in thecomposition is a pharmaceutically acceptable agent.
 9. The method ofclaim 1, wherein the agent has a molecular weight of at least 300daltons.
 10. The method of claim 1, wherein the agent is selected from agroup consisting of peptides, proteins, and polypeptides.
 11. The methodof claim 1, wherein the C₈ -C₁₄ alcohol or unsaturated derivativethereof is present in an amount of about 1 to 50 mM; andthe C₂ -C₄alcohol or unsaturated derivative thereof is present in an amount ofabout 10 to 25% (v/v).
 12. A method of enhancing electrotransport fluxof a beneficial pharmaceutically acceptable agent through a bodysurface, comprising:placing a composition in contact with the bodysurface, at least a portion of the composition being obtained bycombining an agent in a form suitable for electrotransport delivery, atleast one C₈ -C₁₄ linear, branched, cyclic, or aromatic alcohol orunsaturated derivatives thereof, or mixtures thereof, and at least oneC₂ -C₄ alcohol or unsaturated derivatives thereof, or mixtures thereof;and applying an electric field across the composition and the bodysurface, whereby the agent is delivered through the body surface byelectrotransport at a flux greater than in the absence of the alcohols.